Turn Signals: Description and Operation
SYSTEM OPERATIONCombination Flasher
The combination flasher is a smart relay that functions as both the turn signal system and hazard warning system flasher. The combination flasher is designed to handle the current flow requirements of the factory-installed lighting.
If supplemental lighting is added to the turn signal lamp circuits, such as when towing a trailer with lights, the combination flasher will automatically compensate. This allows the flash rate to remain the same, regardless of electrical load increases. However, if a bulb fails in the turn signal lamp circuits, the flash rate of the remaining bulbs in that circuit will increase to 120 flashes-per-minute, or higher.
While the combination flasher shares the terminal orientation (footprint) of a International Standards Organization (ISO) -type relay, the internal circuitry is much different. The combination flasher contains active electronic integrated circuitry elements. Do not substitute any other relay for the combination flasher.
Because of the active electronic elements within the combination flasher, it cannot be tested with conventional automotive electrical test equipment. If the combination flasher is believed to be faulty, test the turn signal and hazard warning system circuits. Then replace the combination flasher with a known good unit to confirm system operation.
The combination flasher cannot be repaired and, if faulty, it must be replaced.
Turn Signal System
With the ignition switch in the On position, and the multi-function switch control lever moved up (right turn) or down (left turn), the turn signal system is activated. The switch has a detent position in each direction that provides turn signals with automatic cancellation, and an intermediate momentary position that provides turn signals only until the multi-function switch lever is released.
When the turn signal switch is in a detent position, it is turned off by one of two cancelling cam lobes molded into the hub of the clockspring mechanism. When turning the steering wheel causes one of the cam lobes to contact a cancel actuator in the multi-function switch, the turn signal switch automatically returns to the off position.
When the turn signal system is activated, the selected (right or left) turn signal indicator lamp, front park/turn signal lamp, front side marker lamp, and rear tail/stop/turn signal lamp bulbs will flash.
Hazard Warning System
The hazard warning system is actuated by a push button located on the top of the steering column between the steering wheel and the instrument panel. The hazard switch is identified with a double triangle on top of the button. Push the button to turn the hazard warning system ON and push the button again to turn the system OFF.
When the hazard warning system is activated, the both turn signal indicator lamps flash in unison with the turn signal lamps, indicating to the driver that the system is operating.
Multi-Function Switch
Multi-Function Switch:
The multi-function switch assembly is mounted to the left side of the steering column. This switch contains circuitry for the following functions:
- Turn signals
- Hazard warning
- Headlamp beam selection
- Headlamp optical horn
- Windshield wipers
- Windshield washers.
The information contained addresses only the switch functions for the turn signal and hazard warning circuits However, the multi-function switch cannot be repaired. If any function of the switch is faulty, the entire switch assembly must be replaced.
Turn Signal Indicator Lamps
The turn signal indicator lamps are located in the instrument cluster. They flash with the exterior turn signal lamps to give the driver a visual indication that a turn signal or the hazard warning system is operating.
Turn Signal Lamps
The exterior lamps in the turn signal and hazard warning circuits include the front park/turn signal, the front side marker, and the rear tail/stop/turn signal.
CIRCUIT OPERATION
Voltage for the turn signals flows from the Power Distribution Center (PDC) to the ignition switch on circuit A2. With the key in the RUN position, the ignition switch connects voltage from the A2 circuit to the A22 circuit. A 30 amp fuse in the PDC protects the A2 and A22 circuits.
Circuit A22 connects to a bus bar in the fuse block. L5 is one of the circuits fed by the bus bar. Circuit L5 contains a 10 amp fuse and supplies voltage to the combination flashing unit (turn signal flasher). Voltage leaves the combination flashing unit on circuit L6 and flows to the multi-function switch connector.
Power is also supplied to the combination flasher on circuit L9. This circuit is HOT at all times and protected by a 20 amp fuse located in cavity 14 of the PDC.
Right Turn Signal
When the operator selects the right turn signal, the multi-function connects power from circuit L6 to circuits L60 and L62. Circuit L60 connects to the multi-function switch and feeds the right front and rear turn signal/hazard flasher/stop lamps.
Circuit L62 is used to power the turn signal indicator lamp on the instrument cluster.
Left Turn Signal
When the operator selects the left turn signal, the multi-function connects power from circuit L6 to circuits L61 and L63. Circuit L63 connects to the multi- function switch and feeds the left front and rear turn signal/hazard flasher/stop lamp.
Circuit L63 is used to power the turn signal indicator lamp on the instrument cluster.
Ground Circuit
Circuit Z1 provides ground for all the turn signal lamps, although the it has different grounding points for each turn signal circuit. Circuit Z1 provides the ground path for the combination flashing unit.